Have a Ducane furnace MPGA100B4B opened the door to inspect the wireing didn't touch anything though today it won't ignite code blinks twice witch is flame roll out switch inducer motor does cycle like normal goes through its checks than gas valve opens four 3 sec than everything turns off and the code starts igniter dosesnt do anything any ideas?

Are you sure the displayed code is flame roll-out limit? Unusual to observe the component functions that you have (inducer, gas control) in conjunction with a flame roll-out fault. A faulty ignitor would produce a fault code relative to flame-proving/ignition failure. Otherwise, it sounds as if the circuit board has experienced some form of internal failure. Check the ignitor for continuity, and that the ignitor is being powered during the ignition trials.